Patent GB-1080565-A (GB)
Title: Method and apparatus for forming a chisel type cutter link
Inventor: NEUMEIER ALBERT
IPC: B23D65/02
Filed: 1964-10-28
Abstract: 1,080,565. Makingsaws; punching. OMARK INDUSTRIES Inc. Oct. 28,1964, No. 43911/64. Headings B3A, B3E, B3H and B3W. A method of cold forming a saw chain cutter link with a cutter portion including a shank portion and a toe portion extending at substantially a right-angle to the shank portion, comprising the steps of first forming a flat metal blank having a body portion and a cutter portion protruding from an edge of said body portion, then partially bending the toe portion relative to the shank portion of the cutter portion to an angle comprising a substantial portion of the final cutter portion angle, then upsetting said cutter portion to increase the thickness of the corner portion resulting from the said partial bending step and to form the final cutter portion angle bend with a sharper exterior corner than that resulting from said partial bending step, and then grinding a cutter edge on the cutter portion. The apparatus for performing the method comprises two sub-sets, in the first of which a partly-formed blank is produced from continuous strip and in the second of which the toe portion of the cutter portion is upset to its final shape. Blanking and initial forming.-A strip of material is fed into the sub-set shown in Fig. 1, in the direction of the arrow, and is flattened by a tool 35 and pierced with two holes 51 by punches 37 at a -first station. At the second station, pilot pins 39 enter the holes 51 and a cutter 41 trims the edge 53. At the third station the metal round the holes 51 is smoothed by a punch 43 and at the fourth station a cutter 43 cuts off a cutter link blank 49 by cutting out a section so as to form the bottom edge 55 and the upper edge 57 of the next link. Pilot pins 61 engage the holes 51 to position the work at the cutting-off station. The blank is pushed by the advancing strip to a bending station at which it is held between a lower member 47 and a spring-loaded upper member 71. Aligning pins 74 pass through the member 71 to position the blank by engaging the holes 51. The cutter portion 65 and a depth gauge portion 67 project from between the members 47 and 71 and are acted on by an upper bending die 90 and a lower bending die 87 to form the blank to the shape shown in Fig. 6, in which the depth gauge part 67 has been bent to its final shape, the shank portion 93 is bent to its final shape and the toe portion 95 of the cutter portion is bent to form an angle of approximately half its final angle with the shank portion. The lower bending die 87 is raised by a rocker arm 82. The end 81 of the rocker arm is depressed against a spring by a stud on the upper platen which acts on a tappet 77. Upsetting.-The partly formed blank 91 is transferred to the second sub-set, Fig. 7, in which it rests on a spring-loaded lower gripper member 107, which is shaped to fit the body portion 63 and the shank portion 93. A complementary upper gripper 129 also engages the partly formed blank, so that the toe portion 65 projects. The upper gripper is mounted on the piston rod 131 of an hydraulic piston and cylinder 127, 121. Fluid can be forced out of the cylinder into a reservoir under pressure so that the hydraulic system acts as a heavy spring. The tool also includes a horizontally slidable plunger 141 which is actuated against a spring 150 by a cam surface 139 associated with the upper platen engaging a co-operating surface 145 on the plunger. When the tool is closed the upper gripper engages the blank and pushes down the blank and the lower gripper 107, until a plate 111 on which the lower gripper is mounted engages a base-plate 117. Further movement of the upper platen causes the piston 127 to be forced into the cylinder 121. At this stage the body and shank of the partly formed blank are completely contained by the upper and lower grippers 129 and 107, the side walls of the socket in which the lower gripper slides, and by pins 119 which enter the holes 51. When the cam surface 139 actuates the plunger 141 it moves to the right and a notch 147 engages the toe 95 and upsets it to give the completely formed cutter shown in Fig. 16. The cavity resulting when the upsetting plunger 141 completes its movement corresponds to the shape of the formed toe portion 151. The cutter is completed by grinding the outer surface of the toe portion along its longitudinal edge 159 and the edges of the toe portion 151 and the shank portion 93 which are directed toward the depth gauge 67.